We intend to investigate a number of functions of the bacterial envelope in relation to the organization and macromolecular composition of the surface elements. The limited number of sites at which some of the cell wall components, such as lipopolysaccharides, are inserted into the growing surface appear to be identical to the sites at which viruses inject their nucleic acids, and at which proteins such as pili, as well as capsular polysaccharides, are synthesized. Recent attempts to isolate these sites were successful and will be continued. In order to study the interrelation of these growth processes with those of virus adsorption and infection, we will employ capsule-producing mutants of Escherichia coli together with viruses that utilize these polysaccharides as receptor. Such cell-virus systems will furthermore permit us to describe the multiple steps of the virus adsorption processes in greater detail than was possible before. Recently we have been able to obtain high resolution x-ray diffraction data from the isolated capsule polysaccharide, and for the first time the conformation of a branched-chain polysaccharide was established. As the next step we will attempt to describe the molecular interaction between the adsorbing virus and its set of receptors. It is hoped that these data will help to provide new insights in virus adsorption phenomena in general. The project will involve virological and immunological methods in combination with electron microscopy and other biophysical and biochemical techniques.